As requirements of high data rate transmission under limited frequency spectra and capital expenses are increasing, applications of the small cell communication system are also rising. In this kind of small cell communication systems, installations of high-density base stations which uses lower transmitting power would become more flexible and economical by separating out remote radio units (RRUs) from baseband units (BBUs) of a base station. One commonly utilized technique would be to keep BBUs in a base station while RRUs could be disposed in one or more remote locations in order to extend the wireless coverage of a base station. When RRUs disposed at remote locations relative to a base station, RRUs could be connected to the BBUs of a base station via an interface, such as a fiber optical interface, and thus RRUs can be deployed at different geographical locations to extend the coverage of a base station.